Encyclopedia of Cancer

2009 Edition
| Editors: Manfred Schwab


  • Lauren M. Nunez
  • Daniel Keppler
Reference work entry
DOI: https://doi.org/10.1007/978-3-540-47648-1_1450


Thiol-protease inhibitors (cytoplasmic α- and β-TPIs; plasma α1- and α2-TPIs); Acid, neutral and basic cysteine-protease inhibitors (ACPI, NCPI and BCPI); Thiostatins


Cystatins were originally defined as endogenous  inhibitors of thiol- or cysteine- proteases. Later, the discoveries of several proteins whose primary sequence revealed substantial homology to the typical cystatin domain led to the definition of a cystatin super-family. With the identification of other types of intracellular cysteine-proteases, however, it became clear that cystatins inhibit mainly cysteine-proteases present in endosomes and  lysosomes. Additionally, many of the newer members of the cystatin super-family have less than 30% homology to classical cystatins and do not inhibit lysosomal cysteine-proteases. Moreover, several proteins with little apparent amino acid sequence homology fold into typical three-dimensional structures attributed to cystatins. Thus, the term “cystatins” now...

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Copyright information

© Springer-Verlag Berlin Heidelberg New York 2008

Authors and Affiliations

  • Lauren M. Nunez
    • 1
  • Daniel Keppler
    • 1
  1. 1.Department of Biological Science, College of PharmacyTouro University-CA1310 Johnson haneVallyo, CA 94592